Hua: Identifying the source of pollutants in Malacca River using GIS approach - 571 - IDENTIFYING THE SOURCE OF POLLUTANTS IN MALACCA RIVER USING GIS APPROACH HUA, A. K. Department of Environmental Sciences, Faculty of Environmental Studies, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia e-mail: [email protected] (Received 19th Mar 2017; accepted 26th Jun 2017) Abstract. The study was conducted to determine the dominant source of pollutants in Malacca River using the combined methods of water sampling and GIS approach. The study was conducted in 9 sampling stations based on Malacca River sub-basins. The result of WQI indicated that station 4 and 5 are polluted; station 8 and 9 are clean; and other stations are slightly polluted. PCA identified several pollutant sources, namely agricultural, residential, industrial, animal husbandry activities, as well as sewage treatment plants. Applied GIS technique detected several areas as hotspots pollutants sources, namely agricultural activities in station 5; residential activities in station 1, 2, 5, 6, and 7; industrial activities in station 3, 4, 5, and 7; animal husbandry in station 5 and some scatterings in station 1 to 4; as well as sewage treatment plant in moderate hotspot area between station 5 and 6, respectively. Besides the recommendation to reduce the river water pollution through the control of pollutants source, this study provides crucial information for the identification of problematic areas and spatial database of Malacca River for better understanding and management of river water quality in the future, as well as a reference for future land use and urban design development purposes. Keywords: WQI, PCA, hotspot analysis, spatial database Introduction River water pollution has received great attention in recent years and continues to receive serious concern throughout the world. Water quality deterioration is primarily connected to the subject of population growth and city expansion. This is a threatening factor to human and ecological health, drinking water availability, and furthermore to the economic development (Houser and Richardson, 2015; Morse and Wolheim, 2014; Li and Zhang, 2010). According to Iscen et al. (2008), surface water is easily exposed to pollution due to its - accessibility to wastewater disposal. Water quality impairment resulted from anthropogenic inputs (e.g. municipal and industrial wastewater discharges, agricultural runoff) and natural processes such as chemical weathering and soil erosion (Shin et al., 2013; Singh et al., 2011; Iscen et al., 2008), contributed to the input of non-point and point source pollutants of the river (Iscen et al., 2008). Therefore, water quality assessment with geographic information system (GIS) is an important tool in identifying possible pollutant sources with the aim to prevent and control water pollution; which is crucial for sustainable water resource use with respect to ecosystem health and social development (Iscen et al., 2008; Shrestha and Kazama, 2007; Zhang, 2006). Malaysia as an ongoing developing country in South East Asia is facing major water quality problems (DOE, 2012). Human activities that generate economic benefit for the society has indirectly deteriorate the water quality of the river (Muyibi et al., 2008). Several studies focused on the assessment of water quality indicated that unsustainable development could result in environmental damage to surrounding areas, as well as to the biodiversity of benthic macroinvertebrates (Al-Shami et al., 2010). Specifically, APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 15(4):571-588. http://www.aloki.hu ● ISSN 1589 1623 (Print) ● ISSN 1785 0037 (Online) DOI: http://dx.doi.org/10.15666/aeer/1504_571588 2017, ALÖKI Kft., Budapest, Hungary Hua: Identifying the source of pollutants in Malacca River using GIS approach - 572 - researchers have identified that wastewater that were discharged from the manufacturing and agro-based industry, domestic sewage, animal husbandry, mining activity, and surface runoff originating from land clearing and earthwork activity; could lead to water resource pollution, especially in the river (DOE, 2012; Suratman et al., 2009; Deb et al., 2008; Ebrahimpour and Mushrifah, 2008; Muyibi et al., 2008). This situation is no stranger to the state of Malacca, which has faced serious water pollution problems that led to the death of aquatic species along the Malacca River (Sinar Harian Online, 2016; Hua, 2015; Metro Online, 2015; Daneshmend et al., 2011). Malacca State was recognized by UNESCO as a World Heritage Site in 2008 (UNESCO, 2016) and since has become a world historical tourism center for the country. This establishment is important for the economic and population growth of Malacca State. Indirectly, Malacca River may not have been exposed to the issues of river water pollution in the past. Nevertheless, the increasing number of population, uncontrolled rapid development, and extreme land use has led to the ‘disruption’ of Malacca River. Besides water quality assessment and monitoring, an applied GIS through hotspot analysis would assist in determining the dominant source of pollution that has greater impact to Malacca River. GIS hotspot analysis is a method that has been frequently applied in various studies in the fields of diseases (Liu et al., 2006), mortality rates (Mclaughlin and Boscoe, 2007), environmental planning, as well as the environmental sciences (Ishioka et al., 2007). For instant, Liu et al. (2006) used GIS to assess and sample the pattern of heavy metal in paddy field; and Zhang (2006) used hotspot analysis of GIS approach to identify the pollutants in urban soils in Ireland. Several GIS analysis methods have been proposed for hotspot analysis, such as spatial scan statistics (Ishioka et al., 2007), Tango’ C index (Zhang and Lin, 2006; Tango, 1995), as well as Getis’s G index (Getis and Ord, 1992). These methods are often used in the field of environmental sciences, planning, and management. Hotspot analysis which is extended from Moran’s I index in spatial analysis, can be classified into two categories, namely global Moran’s I (Oldland, 1998; Cliff and Ord, 1981) and local Moran’s I index (Zhang et al., 2008; Mclaughlin and Boscoe, 2007; Getis and Ord, 1992). Unlike the particular analysis of Moran’s I which only focuses on the detection of similar value clusterings, hotspot analysis technique using G-statistic has the ability to express the high/low value clusterings (Getis and Ord, 1992). This technique of hotspot analysis is applied to this study. The objectives of the study are (1) to identify water quality status and pollution sources using relationship elements of natural origins; and (2) to determine the dominant sources of pollutants through spatial pattern analysis. Materials and Methods Study Area The state of Malacca is located in the southwest of Peninsular Malaysia with the geographical coordinates of 2°23’16.08”N to 2°24’52.27”N latitude and 102°10’36.45”E to 102°29’17.68”E longitude. Malacca is divided into three districts, namely Alor Gajah, Jasin, and Malacca Central. Total catchment area of Malacca is approximately around 670 km2 with about 80 km distance of Malacca River. The basin is formed by 13 sub-basins namely Kampung Ampang Batu Gadek sub-basin, Kampung Balai sub-basin, Kampung Batu Berendam sub-basin, Kampung Buloh China sub-basin, Kampung Cheng sub-basin, Kampung Gadek sub-basin, Kampung Harmoni Belimbing Dalam sub-basin, Kampung Kelemak sub-basin, Kampung Panchor sub-basin, APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 15(4):571-588. http://www.aloki.hu ● ISSN 1589 1623 (Print) ● ISSN 1785 0037 (Online) DOI: http://dx.doi.org/10.15666/aeer/1504_571588 2017, ALÖKI Kft., Budapest, Hungary Hua: Identifying the source of pollutants in Malacca River using GIS approach - 573 - Kampung Pulau sub-basin, Kampung Sungai Petai sub-basin, Kampung Tamah Merah sub-basin, and Kampung Tualang sub-basin (Figure 1). Among the 13 sub-basins, only 7 sub-basins were selected, with 9 sampling stations located alongside Malacca River. Figure 1. Malacca River sub-basin and sampling area APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 15(4):571-588. http://www.aloki.hu ● ISSN 1589 1623 (Print) ● ISSN 1785 0037 (Online) DOI: http://dx.doi.org/10.15666/aeer/1504_571588 2017, ALÖKI Kft., Budapest, Hungary Hua: Identifying the source of pollutants in Malacca River using GIS approach - 574 - Malacca River flows across Alor Gajah to the Malacca Central district before entering into the Straits of Malacca. Alongside Malacca River, there is a reservoir located between Alor Gajah and Malacca Central, namely Durian Tunggal Reservoir, with a catchment area of approximately 20 km2 that act as a source of water supply for Malacca residents. The built-up area is mainly concentrated in the city center, Malacca Central, at a downstream area extending about 10 km to the west, 10 km to the east, and 20 km to the north. The urban land uses are primarily residential and commercial, while several industrial activities including high-technology and estates are located in the middle-stream and upstream areas. Most of the large-scale agricultural activities land use are located upstream. Field Sampling There were 9 sampling stations chosen alongside Malacca River. The locations were determined using a Global Positioning System (GPS) coordinates as shown in Table 1 and the geographic coverage is as shown in Figure 1. The collection of water quality samples were carried out monthly from January to December 2015. Table 1. The latitude and longitude of sampling stations Station Latitude Longitude S1 02°21’57.41”N 102°13’7.10”E S2 02°21’30.16”N 102°13’18.20”E S3 02°20’49.52”N 102°14’36.44”E S4 02°19’41.70”N 102°15’27.30”E S5 02°17’48.86”N 102°15’39.51”E S6 02°15’46.55”N 102°14’10.72”E S7 02°14’5.02”N 102°15’24.67”E S8 02°13’14.33”N 102°14’35.01”E S9 02°12’23.42”N 102°15’0.80”E Source: Global Positioning System The water samples were collected using ‘grab sampling’ technique in the polyethylene bottles without entrapping the air bubbles.